Frequency and/or phase compensated microelectromechanical oscillator

• US 7,453,324 B2
• Filed: 04/30/2007
• Issued: 11/18/2008
• Est. Priority Date: 01/09/2004
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus
• Primary Examiner(s): Mis; David
• Application Number:
  US11/796,990
• Publication Number:
  US 20080150642A1
• Time in Patent Office: 568 Days
• Field of Search: 331/18, 331/66, 331/74, 331/75, 331/116.R, 331/116.FE, 331/116.M, 331/154, 331/156, 331/175, 331/176
• US Class Current: 331/154
• CPC Class Codes: H03B 5/04 Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
• CPC Class Codes: H03B 5/30 with frequency-determining element being electromechanical resonator
• CPC Class Codes: H03L 1/022 by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature H03L1/021 takes precedence
• CPC Class Codes: H03L 1/026 by using a memory for digitally storing correction values H03L1/025 takes precedence
• CPC Class Codes: H03L 1/027 by using frequency conversion means which is variable with temperature, e.g. mixer, frequency divider, pulse add/substract logic circuit H03L1/023, H03L1/026 take precedence
• CPC Class Codes: H03L 1/04 Constructional details for maintaining temperature constant
• CPC Class Codes: H03L 7/07 using several loops, e.g. for redundant clock signal generation
• CPC Class Codes: H03L 7/08 Details of the phase-locked loop
• CPC Class Codes: H03L 7/1974 for fractional frequency division

Abstract

There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a compensated microelectromechanical oscillator, having a microelectromechanical resonator that generates an output signal and frequency adjustment circuitry, coupled to the microelectromechanical resonator to receive the output signal of the microelectromechanical resonator and, in response to a set of values, to generate an output signal having second frequency. In one embodiment, the values may be determined using the frequency of the output signal of the microelectromechanical resonator, which depends on the operating temperature of the microelectromechanical resonator and/or manufacturing variations of the microelectromechanical resonator. In one embodiment, the frequency adjustment circuitry may include frequency multiplier circuitry, for example, PLLs, DLLs, digital/frequency synthesizers and/or FLLs, as well as any combinations and permutations thereof. The frequency adjustment circuitry, in addition or in lieu thereof, may include frequency divider circuitry, for example, DLLs, digital/frequency synthesizers (for example, DDS) and/or FLLs, as well as any combinations and permutations thereof.

Claims

1. A compensated microelectromechanical oscillator, comprising:

a microelectromechanical oscillator to generate an output signal wherein the output signal includes a first frequency, the microelectromechanical oscillator comprises;

a microelectromechanical resonator; and

drive circuitry, coupled to microelectromechanical resonator, to output a drive signal to the microelectromechanical resonator;

control circuitry, coupled to the drive circuitry, to output a control signal which adjusts the drive signal from the drive circuitry; and

frequency adjustment circuitry, coupled to the microelectromechanical oscillator to generate an output signal having a second frequency using the output signal of the microelectromechanical oscillator and a set of values, wherein the second frequency is greater than the first frequency.

2. The compensated microelectromechanical oscillator of claim 1 further including temperature sensor circuitry, coupled to the control circuitry, to provide data which is representative of operating temperature to the control circuitry.

3. The compensated microelectromechanical oscillator of claim 2 wherein the control circuitry determines the control signal using the data which is representative of operating temperature.

4. The compensated microelectromechanical oscillator of claim 3 wherein the control circuitry determines the control signal by calculating the control signal using the data which is representative of operating temperature.

5. The compensated microelectromechanical oscillator of claim 2 wherein the control circuitry determines the control signal using (i) the data which is representative of operating temperature and (ii) empirical data or a mathematical relationship.

6. The compensated microelectromechanical oscillator of claim 1 wherein the set of values is determined, at least in part, using information which is representative of the first frequency.

7. The compensated microelectromechanical oscillator of claim 6 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator.

8. The compensated microelectromechanical oscillator of claim 1 wherein the set of values are determined using empirical data or mathematical modeling.

9. The compensated microelectromechanical oscillator of claim 1 wherein the set of values are determined during (i) testing of the microelectromechanical resonator and/or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, and/or (iii) operation of the microelectromechanical oscillator.

10. A compensated microelectromechanical oscillator, comprising:

a microelectromechanical oscillator to generate an output signal wherein the output signal includes a first frequency, the microelectromechanical oscillator comprises;

a microelectromechanical resonator; and

drive circuitry, coupled to microelectromechanical resonator, to output a drive signal to the microelectromechanical resonator;

control circuitry, coupled to the drive circuitry, to;

(i) determine a control signal using the data which is representative of temperature and (ii) output a control signal which adjusts the drive signal from the drive circuitry;

frequency adjustment circuitry, coupled to the microelectromechanical oscillator to generate an output signal having a second frequency using the output signal of the microelectromechanical oscillator and a set of values, wherein the second frequency is greater than the first frequency; and

memory, coupled to the frequency adjustment circuitry, to store the set of values.

11. The compensated microelectromechanical oscillator of claim 10 further including temperature sensor circuitry, coupled to the control circuitry, to provide data which is representative of an operating temperature to the control circuitry.

12. The compensated microelectromechanical oscillator of claim 11 wherein the memory further stores a look-up table relating the drive signal to an operating temperature.

13. The compensated microelectromechanical oscillator of claim 12 wherein the control circuitry determines the control signal using the data in the look-up table.

14. The compensated microelectromechanical oscillator of claim 11 wherein the control circuitry determines the control signal by calculating the control signal using the data which is representative of temperature.

15. The compensated microelectromechanical oscillator of claim 11 wherein the set of values is determined, at least in part, using information which is representative of the first frequency.

16. The compensated microelectromechanical oscillator of claim 15 wherein the set of values are determined using empirical data or mathematical modeling.

17. The compensated microelectromechanical oscillator of claim 11 wherein the set of values is determined, at least in part, using the operating temperature.

18. The compensated microelectromechanical oscillator of claim 17 wherein the set of values are determined during (i) testing of the microelectromechanical resonator and/or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, and/or (iii) operation of the microelectromechanical oscillator.

19. A compensated microelectromechanical oscillator, comprising:

a microelectromechanical oscillator to generate an output signal wherein the output signal includes a first frequency, the microelectromechanical oscillator comprises;

a microelectromechanical resonator; and

drive circuitry, coupled to microelectromechanical resonator, to output a drive signal to the microelectromechanical resonator;

control circuitry, coupled to the drive circuitry, to output a control signal to the drive circuitry wherein the control signal adjusts the drive signal from the drive circuitry; and

frequency adjustment circuitry, coupled to the microelectromechanical oscillator to generate a plurality of output signals using (i) one or more sets of values and (ii) the output signal of the microelectromechanical oscillator wherein at least one of the output signals includes a frequency that is greater than the first frequency.

20. The microelectromechanical oscillator of claim 19 wherein the frequency adjustment circuitry includes first and second frequency multiplier circuitry which are one or more PLLs and/or one or more digital/frequency synthesizers.

21. The microelectromechanical oscillator of claim 20 wherein the PLLs are one or more fractional-N PLLs and/or one or more integer-N PLLs.

22. The microelectromechanical oscillator of claim 19 wherein the frequency adjustment circuitry includes first and second frequency multiplier circuitry and wherein:

the first frequency multiplier circuitry is a fractional-N PLL, an integer-N PLL, or a digital/frequency synthesizer; and

the second frequency multiplier circuitry is a fractional-N, PLL, an integer-N PLL or a digital/frequency synthesizer.

23. The microelectromechanical oscillator of claim 19 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator and wherein the microelectromechanical oscillator further includes temperature sensor circuitry to determine information which is representative of the operating temperature of the microelectromechanical resonator, an operating temperature of the microelectromechanical oscillator or an operating temperature of the frequency adjustment circuitry.

24. The microelectromechanical oscillator of claim 23 wherein the values are determined during (i) calibration of the microelectromechanical oscillator or (ii) operation of the microelectromechanical oscillator.

25. The microelectromechanical oscillator of claim 23 further including temperature sensors to provide data which is representative of temperature to the temperature sensor circuitry.

26. The microelectromechanical oscillator of claim 19 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator and wherein the microelectromechanical oscillator further includes temperature sensor circuitry, integrated in or on the common substrate, to determine information which is representative of (i) an operating temperature of the microelectromechanical resonator, (ii) an operating temperature of the microelectromechanical oscillator or (iii) an operating temperature of the frequency adjustment circuitry.

27. The microelectromechanical oscillator of claim 26 wherein the values are determined during (i) calibration of the microelectromechanical oscillator or (ii) operation of the microelectromechanical oscillator.

28. The microelectromechanical oscillator of claim 26 wherein more than one of the output signals include frequencies that are greater than the first frequency.

29. The microelectromechanical oscillator of claim 26 further including temperature sensors, integrated in or on the common substrate, to provide data which is representative of temperature to the temperature sensor circuitry.

30. A compensated microelectromechanical oscillator, comprising:

a microelectromechanical oscillator to generate an output signal wherein the output signal includes a first frequency, the microelectromechanical oscillator comprises;

a microelectromechanical resonator; and

drive circuitry, coupled to microelectromechanical resonator, to output a drive signal to the microelectromechanical resonator;

temperature sensor circuitry, coupled to the control circuitry, to provide data which is representative of an operating temperature to the control circuitry;

control circuitry, coupled to the drive circuitry and temperature sensor circuitry, to;

(i) determine a control signal using the data which is representative of an operating temperature and (ii) output a control signal which adjusts the drive signal from the drive circuitry; and

frequency adjustment circuitry, coupled to the microelectromechanical oscillator to generate a plurality of output signals using (i) one or more sets of values and (ii) the output signal of the microelectromechanical oscillator wherein at least one of the output signals includes a frequency that is greater than the first frequency.

31. The compensated microelectromechanical oscillator of claim 30 further including a memory, coupled to the frequency adjustment circuitry, to store the values.

32. The compensated microelectromechanical oscillator of claim 30 further including a memory, coupled to the control circuitry, to store a look-up table relating the drive signal to an operating temperature.

33. The compensated microelectromechanical oscillator of claim 32 wherein the control circuitry determines the control signal using the data in the look-up table.

34. The compensated microelectromechanical oscillator of claim 30 wherein the control circuitry determines the control signal by calculating the control signal using the data which is representative of temperature.

35. The compensated microelectromechanical oscillator of claim 30 wherein the set of values is determined, at least in part, using information which is representative of the first frequency.

36. The compensated microelectromechanical oscillator of claim 35 wherein the set of values are determined using empirical data or mathematical modeling.

37. The compensated microelectromechanical oscillator of claim 30 wherein the set of values is determined, at least in part, using the operating temperature.

38. The compensated microelectromechanical oscillator of claim 37 wherein the set of values are determined during (i) testing of the microelectromechanical resonator and/or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, and/or (iii) operation of the microelectromechanical oscillator.

39. The microelectromechanical oscillator of claim 30 wherein the frequency adjustment circuitry includes first and second frequency multiplier circuitry which are one or more PLLs and/or one or more digital/frequency synthesizers.

40. The microelectromechanical oscillator of claim 39 wherein the PLLs are one or more fractional-N PLLs and/or one or more integer-N PLLs.

41. The microelectromechanical oscillator of claim 30 wherein the frequency adjustment circuitry includes first and second frequency multiplier circuitry and wherein:

the first frequency multiplier circuitry is a fractional-N PLL, an integer-N PLL, or a digital/frequency synthesizer; and

the second frequency multiplier circuitry is a fractional-N, PLL, an integer-N PLL or a digital/frequency synthesizer.

42. The microelectromechanical oscillator of claim 30 wherein more than one of the output signals include frequencies that are greater than the first frequency.